travis build changes

- Update go version to 1.9.
- add go generate step.

.travis.yml

@@ -4,7 +4,7 @@ dist: trusty
 sudo: require
 
 go:
-  - 1.7
+  - 1.9
 
 env:
   - LIBVIRT=1.2.2  EXT=gz
@@ -41,9 +41,11 @@ before_script:
   - sudo virsh start test
   - sudo virsh pool-create .travis/test-pool.xml
   - sudo virsh secret-define .travis/test-secret.xml
+  - go get github.com/golang/x/tools/cmd/goyacc
 
 script:
   - ./scripts/licensecheck.sh
+  - LIBVIRT_SOURCE=/usr/src/libvirt-${LIBVIRT} go generate ./...
   - go build ./...
   - golint -set_exit_status ./...
   - go vet ./...